Does photo prove a shark's loose in the Tyne?

Philip Walker, 43, photographed a creature with a familiar-looking large dorsal fin as it made its way towards his boat near the port's fish quay. It circled the vessel several times and even bumped into the boat before swimming down the Tyne towards the North Sea.

"It was about 3am or 4am and I just saw it going round and round the harbour," said Mr Walker, 43, who was fishing for cod and mackerel with his son David, 13, when they both spotted the fish.

"It was among all the boats and just kept circling round then it came close to us and hit our boat," he recalled. "I was waiting with the camera but it just smashed into the side and [David] was convinced it was coming to get us."

It is the second apparent sighting of a shark in North Shields as many weeks. Last week, an 8ft porbeagle shark showed up. Another North Shields fishermen who claimed earlier this year to have seen a blue shark - one of the fastest swimmers in the world - suddenly seems less deluded than many locals considered him at the time.

The Walkers had been out in their boat, a Hardy Pilot craft, for five minutes when they spotted the creature. Mr Walker, a courier, waited until his film had been developed before he could believe what he had seen and took the results to a friend for confirmation.

Zahra d'Aronville of the Blue Reef Aquarium in nearby Tynemouth was less convinced. "I don't think it's a shark because it is breaching the surface of the water and that is more characteristic of a mammal such as a porpoise, a dolphin or a minke whale," he said.

But Mr Walker said: "I go out in my boat a lot and I've seen dolphins before and they are nothing like this.

"When we saw it, there was a party going on with five or six other vessels and about 30 people saw it. Some of them reported it, but I have the proof. I'm frightened because a lot of people use that area around North Shields and now there is a shark out there."

Sharks are rarely seen in such northerly locations. Sightings are more usually reported off Cornwall, with recent sightings of a 6ft bull shark near Penzance and three makos.